The present invention relates to masonry construction, and more particularly pertains to an improved mortar extrusion gun especially adapted for use in applying mortar in joints formed between adjacent masonry construction units such as bricks, tiles, stones, pavers, and the like. In the initial construction and repair of masonry structures such as walls, fireplaces, chimneys, patios, etc., it is frequently necessary to apply mortar into the joint region formed between two adjacent masonry construction units. In the past, this operation, known as "tuck pointing", has been typically performed by (1) mixing a relatively stiff mortar mix from cement, sand, lime, and water; (2) holding a quantity of the mortar mix on a trowel adjacent the joint area; and (3) manually "stuffing" the joint with mortar from the trowel utilizing a so-called "tuck pointer" tool. This prior art manual method is disadvantageous for many reasons. First, the process is slow and tedious. Second, the relatively stiff (dry) mortar dries rapidly and is thus difficult to work with, particularly on large jobs. Third, the manual stuffing method tends to result in uneven joints possessing irregular depth and thickness and tends to smear the face of the bricks with mortar. Fourth, the manual stuffing tuck pointing technique requires a great deal of practice to perform at commercially acceptable levels of quality and speed. Fifth, the dry mortar required for manual stuffing is difficult to introduce into narrow and/or deep mortar joints and has reduced adhesion to old, dry bricks compared with a looser, wetter mortar mixture. Accordingly, it is essentially impossible to apply a thin veneer of new mortar over old mortar joints when repairing a masonry structure, which is necessary to produce an aesthetically acceptable result.
Several alternative solutions have been proposed in the prior art in attempts to solve these problems. One prior art method, seldom used by professionals, involves the filling of an open ended squeezable bag possessing an application nozzle with mortar and manually squeezing the bag to extrude mortar from the bag through the nozzle and into the mortar joint. This so-called "grout glove" method has been found disadvantageous because of the difficulty in filling the bag, the difficulty in expressing mortar from the bag into the desired joint area at a uniform rate, and the tendency of the application nozzle to clog results in commercially unacceptable levels of quality and speed. Further, the grout glove is very messy and difficult to use, partially because of its open ended construction. The grout glove method also suffers from very inaccurate pressure and flow control, a requirement for stiff, dry mortar, and messy and incomplete injection of mortar into masonry joints.
Still another prior art attempt to solve the uniform application rate, quality, and speed problems involves the use of a variable speed electric pump which pumps mortar from a hopper through a hose to an application nozzle. Controls located at the nozzle regulate pump speed to control mortar application rates. A motor actuated paddle maintains the mortar homogeneously mixed within the hopper. Nonetheless, this pump method has several serious disadvantages. First, a large amount of mortar must be mixed to operate the system, even for very small jobs. Second, the supply hose introduces a large amount of friction, resulting in frequent clogging. Third, the system requires a relatively large mortar extrusion aperture to avoid constant clogging, and is thus not suited for use with narrow mortar joints. Fourth, the pump system lacks adequate pressure and volume flow rate control. Fifth, the system requires two experienced workmen to operate properly. Sixth, the system is prohibitively expensive for most applications.
Reloadable caulking guns known for the application of latex and silicone caulking compounds are available from Albion Engineering Company of Philadelphia, Pa. These so-called bulk load guns employ a threaded loading sleeve and threaded adaptor ring for a cone tip, both of which must be screwed on and off while manually holding the long heavy gun in a vertical orientation. Threaded connections are incompatible with mortar applications due to the abrasive nature of the cementitious particles, which foul and rapidly wear mating threads. The bulk load guns are difficult to clean and possess exposed internal working parts which would be subject to damage if exposed to contact with abrasive cementitious particles. Due to the short set up time of mortar in tuck pointing, a workman would need to purchase about eight relatively expensive bulk load guns to perform at acceptable production rates.